1. Field of the Invention
The present invention relates to dental implements. More specifically, it relates to a dental implement that uses pressurized medical grade nitrogen to impel granules of aluminum oxide entrained in the nitrogen flow for use in preparing a tooth for receiving a filling or composite restoration.
2. Description of the Prior Art
A new trend in dentistry is to replace the conventional, well known drill with a high velocity stream of gas having entrained particles within it. This allows for removal of the decayed area or old filling in or on the tooth's surface without heat or shock, and in many cases, without the use of anesthetics. Additionally, the surface is roughened during the process, which promotes better bonding with the composite material. One of the drawbacks of other intraoral air abrasive devices is their prohibitive cost. With the overhead burden on dentists already being extraordinarily high, this precludes many practitioners from obtaining them.
There have been a great many patents issued that relate to the present invention, and they will be discussed hereinafter, grouped according to the general thrust of their subject material.
The first group are the patents that deal specifically with entrained particles in a stream having a dental application.
In U.S. Pat. No. 3,626,841, issued on Dec. 14, 1971 to Zvi Harry Schachter there is disclosed an abrasive propellant apparatus. The mixing chamber of the device has a length of tubing having a threaded end. There is a cap having a flowable material inlet orifice at the base of the tube proximate the flexible conduit that connects the nozzle to the mixing chamber. This is an extraoral device that would be used for lab work. U.S. Pat. No. 4,941,298 issued on Jul. 17, 1990 to Mark Fernwood et al. discloses a rear reservoir micro sandblaster. In this invention, the body of the device has a pulverant material supply tube and a compressed air supply line. The compressed air supply tube is compressed by a pinch lever and, if this lever is depressed to allow the air to flow, a vacuum is created in the vortex chamber proximate the nozzle, which draws the pulverant material from the reservoir to the vortex chamber to mix with the gas, and thus be propelled out the nozzle. In contradistinction to the present invention, the Fernwood et al. device is primarily an extraoral device that, when used intraorally, is utilized for the repair of fixed prosthetics.
In U.S. Pat. Nos. 3,972,123 and 3,882,638 issued, respectively, on Aug. 3, 1976 and May 13, 1975, both to Robert B. Black there is disclosed air-abrasive prophylaxis equipment. Centrally disposed within the abrasive mixing device is a receptacle to receive the gasses, containing ports to mix the abrasive and the air as it is passed through. The abrasive laden gas is then directed through a controlling pinch valve to the hand piece.
Next is U.S. Pat. No. 4,174,571 issued on Nov. 20, 1979 to Ben J. Gallant. In this document, a method for cleaning teeth using water soluble abrasive particles is disclosed.
In U.S. Pat. No. 4,214,871 issued on Jul. 29, 1980 to Carter H. Arnold, there is disclosed a method and apparatus for cleaning teeth. The method disclosed involves water soluble halite pellets entrained within a liquid stream.
In U.S. Pat. No. 4,487,582 issued on Dec. 11, 1984 to George E. Warrin there is disclosed a dental cleaning system wherein a stream of soluble abrasive powder entrained in a stream of air is surrounded by a water spray curtain and directed at the surface of a tooth to clean the same.
The second group of patents are related to entrained abrasives in an air flow. These patents are listed below but will not be discussed in detail.
______________________________________ PAT. NO. INVENTOR DATE OF ISSUE ______________________________________ 3,163,963 Racine Caron January 5, 1965 3,618,263 Per Torsten Weijsenburg November 9, 1971 4,090,334 Benedict Kurowski May 23, 1978 4,708,534 Ben J. Gallant November 24, 1987 4,733,503 Ben J. Gallant et al. March 29, 1988 4,893,440 Ben J. Gallant et al. June 16, 1990 DE 2314294 Robert B. Black October 18, 1973 ______________________________________
The next group of patents relate to tubal flow shutoff mechanisms. First is U.S. Pat. No. 3,759,483 issued to Thomas D. Baxter on Sep. 18, 1973. This control valve has a pair of ports that drive a piston connected to a cam member. When the piston travels, the attached camming member drives one of the two valve closure members towards the other, crimping the flexible conduit that lies between them.
Another tube flow shutoff device is seen in U.S. Pat. No. 4,635,897 issued on Jan. 13, 1987 to Ben J. Gallant. In this patent, a plunger cuts off the flow in the tube. The plunger is driven by a cylinder and piston arrangement that, in turn, is driven by compressed air or the like.
Another group of patents relevant to the present invention are those dealing with fiber optics associated with dental handpieces. First of these is U.S. Pat. No. 5,088,924 issued on Feb. 18, 1992 to Gary Woodward. This discloses a dental headpiece hose that with a plurality of inner components to provide drive air, an exhaust line, chip air, and coolant water. The hose also contains a fiber optic bundle for lighting the working area.
The other patent in this group is U.S. Pat. No. 5,096,418 issued on Mar. 17, 1992 to Ronald G. Coss. The device has a special channel within it to carry a fiber optic bundle for lighting the work area.
U.S. Pat. No. 3,067,765 issued on Dec. 11, 1962 to Robert H. Aymer et al. discloses a foot control for dental accessories.
And lastly, an American Dental Laser (ADL) brochure delineating the advantages of this type of device is enclosed. Unlike the present invention, the ADL device utilizes compressed air from the dentist's existing supply and further compresses this air to achieve a cutting level.
The present invention allows the practitioner to simply detach the standard air driven drill from the existing airflow control means and plug the air transport hose, with its conventional four hole connector, into the control unit of the instant invention for nitrogen flow control purposes. The present invention also allows for more inexpensive construction in that the pressures being generated at points along the gas flow and abrasive entraining route never exceed 170 PSI.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.